Working machines are in particular machines which, in accordance with their design and the particular equipment permanently fixed on the vehicle, are intended and suitable for carrying out work but not for transporting people or goods. For example, they include agricultural or forestry machines, or also building machines. In particular but not exclusively, in the context of building machines wheel loaders, mobile baggers or also tipper vehicles (for example so-termed dump-trucks) can be mentioned.
In working machines power-split transmissions, in particular mechanical/hydrostatic power-split transmissions are often used. When a travel direction reversal is required, a reversing clutch for the current travel direction is opened and a reversing clutch for the new travel direction is closed. Here it is also known that control variables are used for the opening and closing of the reversing clutches, and for determining the control variables a rotational factor and a translational factor are taken into account. In this context the rotational factor relates to the proportion required for the rotation of the internal rotating masses in the transmission. In a general sense the rotational factor represents the fraction of the moment of inertia of the transmission in the reversing process. The translational factor, in contrast, includes above all else the theoretical vehicle mass and the preselected or required reversing dynamic.
From EP 1 097 318 B1 by the present applicant it is known to initiate a travel direction reversal automatically even at high speeds, by first reducing the travel speed to a lower value by increasing the transmission ratio of a transmission with continuously variable ratio. Then, an open clutch for the new travel direction and a closed clutch for the previous travel direction are each brought to slipping operation, whereby the drive torque is transferred without interruption and without any jerking from the previously closed clutch to the previously open clutch. The previously closed clutch is steadily opened further until it is operating without slip. The previously open clutch remains in slipping operation until the vehicle is first braked and then accelerates in the new travel direction, until the driven side and the drive output side of the previously open clutch have reached synchronous speed. Further, the document discloses ways in which the driver can intervene, by actuating the clutch, brake or accelerator pedal, whereby the reversing process can be slowed down or accelerated.
A disadvantage of the known solutions is that in working machines with an automated reversing process, the control variables are pre-set with reference to fixed parameters. Thus, the reversing process of the working machine is carried out under constant conditions. This has the negative consequence that, on the one hand, for the driver the behavior of the vehicle is not always easy to understand and sometimes not reliably reproducible, and on the other hand, non-optimal reversing processes result in poorer quality of the reversing process and ultimately, therefore, to lower productivity/efficiency of the working machine. Furthermore the wear, especially that of the reversing clutches is substantially increased. According to the aforesaid EP 1 097 318 B1 by the present applicant, it is known that the reversing process can be influenced by actuating the clutch, brake or accelerator pedal, which amounts to an intervention based upon the driver's subjective estimation which does not necessarily result in power- and wear-optimized operation of the working machine.